Treatment of silk, and product



Patented Apr. 16,1940 I UNITED STATES 2,196,986 TREATMENT OF SILK, ANDPRODUCT Alessandro Gandini, Monza, Italy No Drawing. Application October26, 1937,

Serial No. 171,097

11 Claims.

The invention relates to a method for the processing of silk fibers, andto a product produced thereby. More particularly, it iscQncerned with amethod for the treatment of silk waste, and to l the silk fibrous massobtained therefrom, and includes correlated improvements and discoverieswhereby the qualities of silk fibers are enhanced.

The processing of silk heretofore, for the purpose'of separating thefibers, entailed a removal of the sericin or gum which cements or holdsthe fibers together. This sericin was removed, by placing the silk in analkaline or acid bath and heating substantially to the boiling pointwhereoy the gum or sericin was removed from the fiber by solution. Suchprocedure employed baths containing to soap or sodium carbonate, or abath containing 1 to 2% sulfuric acid or 2 to 3% hydrochloric acid, andthe like; in all of which procedures it will be noted a marked change in20 the silk fiber was occasioned due to the removal of the sericin.

It is an object of this invention to provide a method for processingsilkwhich renders it well adapted for and capable of conversion into a yarn35 with retention of substantially the natural content of sericin.

Another object of the invention is to provide a method wherebytheprocessingof silkmaybereadily, economically and efliciently carried outcommercially, with obtainment of silk fibers that are hygroscopic,rugged, elastic, and non-conducting of electricity.

' A further object of the invention is to provide a method for thetreatment of silk waste in a manner such that the fibers are soconditioned that they may be carded and combed to produce a staple fiberwhich may be spun into a yarn with facility.

0 An additional object of the invention is a method for the treatment ofsilk waste whereby a staple fiber for conversion into a yarn is obtainedin conjunction with a mattable by-product which is well adapted forfelting, either alone or in admixture with other materials, as hair andwool.

A still further object of the invention is to modify the sericin contentof silk fibers in a manner such that the adherent qualities thereof arelargely if not entirely obviated while the hygroscopicity of the fibersis retained and the fibers are readily separable.

A specific object of the invention is to effect a modification of silkfibers in silk waste by a sub-- and for a period suflicient to bringabout the desired modification of the fibers. V

Other objects of the invention will in part be obvious and will inpartappear hereinafter.

The invention accordingly comprises the seva eral steps and the relationof one or more of such steps with respect to each of the others, and theproduct possessing the features, properties, and the characteristicswhich are exemplified in the following detailed disclosure, and thescope of the 10 invention will be indicated in the claims.

Silk, which may be in the form of waste, may be modified and adapted forthe production of yarn by freeing it from the gum or sericin which is anatural component, or by altering the sericin 5 so that the adherentproperties which attend it in its natural condition are substantiallyremoved. Thereby the fibers are so changed that by carding and combingthere is obtained a staple fiber which may be spun into a yarn, orothergo wise utilized. I

In the practice of the invention, silk fibers are treated in a mannersuch'that the sericin is not removed, but the adherent properties arealmost wholly obviated and the fibers thereby become 25 readilyseparable with a retention of their hygroscopic properties. This may beeffected by treating silk, more especially a silk waste, with a solutioncontaining a substance capable of removing andin an amount suflicient toremove substantially all of the adherent properties of sericin, butwithout any material destruction of the hygroscopicity of the silkfibers. More particularly, the treatment comprises immersing silk in abath containing a substance such as above defined, and specifically ametallic salt belonging to the group consisting of soluble salts, aschlorides, nitrates, sulfates, acetates of cadmium, bismuth, antimony,cobalt and aluminum. These salts preferably are in the form of sulfates,which may be either simple, double or complex.

Moreover the treating substance may be a member of the group .consistingof oxybenzoic acid, salicylic acid and coumarin. An amount of thecompound is dissolved in water to give a concentration upwards to 10%,and such solutions are utilized for the processing of the silk. Thetemperature at which the procedure may be carried out is ordinary roomatmospheric temperatures, and while the period of treatment may vary, ithas been found desirable, and satisfactory results have been obtained,by an immersion offrom two to three hours. Following the period oftreatment the silk is removed from the bath, freed from adheringsolution or aqueous bath liquid by centrifuging, and purified byimmersing in water, centrifuging and then again immersing in water andcentrifuging with a final drying.

The silk obtained by the processing just described retains substantiallyits natural content of sericin with a substantial obviation oftheadherent qualities and a rending insoluble in ammonia and organicacids, as acetic and formic acids. There is obtained a fiber which ishygroscopic, elastic, rugged, and a non-conductor of electricity, sothat it does not readily become disordered and knotted, and uponcarding, combing and spinning yields from a waste a relatively highpercentage of yarn with an accompanying by- -product which, because ofits hygroscopic and 100 parts of silk are immersed in from 700 to 800parts of an aqueous solution of a metallic salt, thus a sulfate ofaluminum in a concentration of, from 1 to 3%. The silk is permitted toremain in the bath or in contact with the solution for a period of from2 to 3 hours and at atmospheric temperatures. During this period aportion of the silk may be removed at intervals for the purpose ofdetermining the separability of the fibers and the condition oradherence of the sericin. When it is found that the fibers may bereadily separated, and that the adherent properties of the sericin havebeen substantially removed, the silk is taken from the bath andseparated from the solution or aqueous bath clinging to it bycentrifuging. Following this the silk may be repeatedly rinsed in coldwater with intervening centrifuging, and finally dried. After drying itmay be passed through a beating process and then combed and carded,yielding a staple fiber which may be spun into yarn.

As a result of the foregoing process there may be obtained from 100parts of silk parts of treated material which, when carded and combed,gives from 70 to 73 parts of staple fiber and as a by-product 8 to 10parts of a silk mass which may be cut and made into a felt incombination with other felting materials, as hair and wool. Theby-product consequently is not a waste material, but is useful and ofvalue. This is in marked contradistinction to former methods in whichparts of silk would yield, after boiling in a soda bath, for example,about '70 parts of silk which, when carded and combed would give about50 to 52 parts of staple and from 18 to 20 parts of a byproduct which isof little value, is not capable of being felted, and has few industrialuses.

Example II Silk cocoons may be treated so that the fibers are readilyseparable and the adherent qualities of the sericin substantiallyobviated by first extracting the oil present in the cocoon by a suitablesolvent material. Having completed the extraction of the oil, 100 partsof the extracted cocoon material may be immersed in 700 to 800 parts ofan aqueous bath containing 2 to 3% cadmium sulfate, and the cocoonallowed to remain therein for a period of time. The remaining steps ofthe treatment are then the same as set forth in Example I.

This treatment yields a cocoon mass from each 200 lbs. of treatedmaterial.

which the fibers may be readily separated, and

gives about 65 to 70% of treated material. which contains about 40 to42% of silk, and after carding and combing gives 28 to 29% of a staplefiber and a lay-product silk mass which, after cutting, may bemanufactured into a felt and other articles.

Example III 100 parts of silk waste are immersed in 700 to 800 parts ofa bath containing a water solution of salicylic acid in a concentrationof 7 to 10%.

'Ihe silk is allowed to remain in the bath, as in Example I, and theother procedural steps are as given therein.

In the foregoing processing the final treatment is by rinsing in waterfollowed by centrifuging with a final drying. This treatment entails theuse of from 8 to 10 cubic meters of water for Moreover, the processingof the silk leads to the obtainment of a silk fiber having markedhygroscopic characteristics and a staple yarn which in amount isconsiderably more than that produced by previous procedures.

The retention of the sericin in a non-adherent condition and. withoutloss of hygroscopicity makes the fiber well suited for conversion into astaple which may be spun into' yarn, and the procedure whereby theimproved fiber is oblainedis materially less costly than the formerprocess of boiling to remove the sericin, inasmuch as a given quantityof finished product requires a lesser quantity of raw material, and inview of the fact that there is'a decided saving in both time and labor..The fiber obtained is characterized by being'soft, hygroscopic,non-adherent, elastic, rugged, and a non-conductor of electricity.

Moreover, when the fibers are spun into yarn and the yarn wovenintogoods, these fibers remain in the positions in which they wereplaced in the woven material and do not tend to slide from suchpositions so that the woven goods possess the quality of maintaining itswoven features without displacement of fibers through stretching orotherwise.

In addition, the fibers can be bleached without loss of weight, andtherefore can be dyed with light colors as well as 'with dark colors.The dyeing may be carried out either with the fibers in the yarn stateor after weaving. When dyeing, the various acid colors may be utilizedand the dyed material is resistant to light andother atmosphericconditions.

It may be added that the procedure for purification followed in thepresent process leads to economies and may be carried out with greaterfacility than the method heretofore employed. It has been usual torinse. the material following treatment to remove the sericin, byplacing it under a jet of water having a pressure of 75 to 90- lbs. anda flow of from 90 to 100 gallons per secend. By the process hereindescribed the use of water under pressure is not necessary, and onlyabout one-one hundredth ofthe quantity of water previously used isrequired. Further, no

out departing from its scope, it is intended that all matter containedin the above description shall be interpreted as illustrative and not ina limiting sense.

It is also to be understood that the following properties of'ithe claimsare intended to cover all of the generic and specific features of theinvention herein described, and all statements of the scope of theinvention which, as a matter of language, might be said to falltherebetween.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

1. A method for processing'silk, which comprises treating silk fiberwith an initial aqueous solution containing from about 1% to about 10%of a metallic salt belonging to the group consisting of soluble salts ofcadmium, bismuth, antimony, cobalt and aluminum whereby substantiallyall of the adherent properties of sericin are removed while retainingthe sericin on the fiber and without destroying the hygroscopicproperties of the silk fiber, and at substantially ordinarytemperatures.

2. A method for processing silk, which comprises treating fiber with aninitial aqueous solution containing from about 1% to about 10% of ametallic salt belonging to the group consisting of soluble salts ofcadmium, bismuth, antimony, cobalt and aluminum whereby substantiallyall of the adherent'properties of sericin are removed' while retainingthe sericin on the fiber and without destroying the, hygroscopic silkfiber, and at substantially ordinary temperatures for a period of from 2to 3 hours and with a quantity of solution substantially '1 to 8 timesthat of the silk.

3. A for processing silk, which comprises treating silk fiber with aninitial aqueous solutionficontaining upwards to 10% of a metallic saltbelonging to the group consisting of soluble saltsof cadminm, bismuth,antimony, cobalt and aluminum, whereby substantially all of the adherentproperties of sericin are removed while retaining the sericin on thefibers and without datroying the hygroscopic properties of the silk 11r.

4. A method for processing silk, which comprises treating silk fiberwith an initial aqueous solution containing from about 1% to about 10%of a sulfate of aluminum whereby substantially all of the adherentproperties of sericin are removed while retaining the serlcin on thefibers and without destroying the hygroscopic properties of the silkfiber.

5. A method for processing silk, which comprises treating silk fiber inan initial aqueous bath containing from 1 to 3% of a sulfate of aluminumfor a period of 2 to 3 hours at atmospheric temperatures wherebyvsubstantially all of the adherent properties of sericin are removedwhile retaining the sericin on the fibers and without, destroying thehygroscopic properties of the silk fiber.

6. A method for processing silk, which comprises treating silk fiber inan aqueous bath containing from 1 to 3% of a sulfate of aluminum for aperiod of 2 to 3 hours at atmospheric temper atures, freeing the fiberfrom adhering aqueous bath by centrifuging, then immersing in water,again centrifuging, immersing another time in water, and finallycentrifuging and drying.

7. A method for processing silk, which comprises extracting oil fromtreated silk cocoons, immersing the so treated cocoons in an initialaqueous bath containing from about 1% to about 10% of a metallic saltbelonging to the group consisting of soluble salts of cadmium-bismuth,antimony, cobalt and aluminum whereby'substantially all of the adherentproperties of sericin are removed while retaining the sericin on thefibers and without destroying the hygroscopic properties of the silkfiber at ordinary temperatures, freeing the thustreated cocoons fromadherin'g aqueous bath by centrifuging, and then purifying by repeatedimmersion in water, centrifuging, and finally drying.

8. As an article of manufacture a silk fiber carrying substantially itsnatural content of sericin, said cericin being in modified conditionsothat it is substantially without adherent properties, insoluble inammonia and acetic and formic acids, said fibers possessinghygroscopicity, elasticity, ruggedness, non-conductability ofelectricity, capable of dry spinning and of being dyed with acid colorsin the usual manner, and obtainable by the method defined in claim 4..

9. As an article of manufacture, silk waste in which the fibers arereadily separable, said fibers carrying substantially their naturalcontent of sericin which is in modified condition so that it issubstantially without'adherent properties, insoluble in ammonia andacetic and formic acids and possessing hygroscopicity, elasticity,ruggedness, non-conductability of electricity, capable of dry spinningand of being dyed with acid colors in the usual manner, and obtainableby the process defined in claim 5.

10. A method for processing silk, which comprises treatlng silk fiber inan initial aqueous bath containing upwards to about 10% of sulfate ofaluminum for a period of two to three hours at atmospheric temperatures,freeing the fiber from adhering aqueous bath, then immersing in water,again freeing the fiber from adhering aqueous bath, immersing anothertime in water, and finally freeing from adhering aqueous bath, anddrying.

11. A method for processing silk, which comprises treating silk fiber inan initial aqueous bath containing from about 1% to about 10% of ametallic salt belonging-tothe group consisting of soluble salts ofcadmium, bismuth, antimony, cobalt and. aluminum for a period of two tothree hours at atmospheric temperatures, freeing the fiber from adheringaqueous bath by centrifuging, then immersing in water, againcentrifuging, immersing another time in water, and finally centrifugingand drying.

. ALESSANDRO GANDINI.

